Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH 1/5] pstore: Remove worse-case compression size logic | Date | Mon, 17 Oct 2022 19:08:09 -0700 |
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The worst case compression size is always the size of the uncompressed data itself so avoid perfectly optimizing the oops buffer size. Hugely simplifies the code.
Cc: Tony Luck <tony.luck@intel.com> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Nick Terrell <terrelln@fb.com> Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/pstore/platform.c | 144 +++---------------------------------------- 1 file changed, 9 insertions(+), 135 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index cbc0b468c1ab..ef0bc3ae161b 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -97,11 +97,6 @@ MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)"); /* Compression parameters */ static struct crypto_comp *tfm; -struct pstore_zbackend { - int (*zbufsize)(size_t size); - const char *name; -}; - static char *big_oops_buf; static size_t big_oops_buf_sz; @@ -168,105 +163,6 @@ static bool pstore_cannot_block_path(enum kmsg_dump_reason reason) } } -#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS) -static int zbufsize_deflate(size_t size) -{ - size_t cmpr; - - switch (size) { - /* buffer range for efivars */ - case 1000 ... 2000: - cmpr = 56; - break; - case 2001 ... 3000: - cmpr = 54; - break; - case 3001 ... 3999: - cmpr = 52; - break; - /* buffer range for nvram, erst */ - case 4000 ... 10000: - cmpr = 45; - break; - default: - cmpr = 60; - break; - } - - return (size * 100) / cmpr; -} -#endif - -#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS) -static int zbufsize_lzo(size_t size) -{ - return lzo1x_worst_compress(size); -} -#endif - -#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS) -static int zbufsize_lz4(size_t size) -{ - return LZ4_compressBound(size); -} -#endif - -#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS) -static int zbufsize_842(size_t size) -{ - return size; -} -#endif - -#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS) -static int zbufsize_zstd(size_t size) -{ - return zstd_compress_bound(size); -} -#endif - -static const struct pstore_zbackend *zbackend __ro_after_init; - -static const struct pstore_zbackend zbackends[] = { -#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS) - { - .zbufsize = zbufsize_deflate, - .name = "deflate", - }, -#endif -#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS) - { - .zbufsize = zbufsize_lzo, - .name = "lzo", - }, -#endif -#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) - { - .zbufsize = zbufsize_lz4, - .name = "lz4", - }, -#endif -#if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS) - { - .zbufsize = zbufsize_lz4, - .name = "lz4hc", - }, -#endif -#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS) - { - .zbufsize = zbufsize_842, - .name = "842", - }, -#endif -#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS) - { - .zbufsize = zbufsize_zstd, - .name = "zstd", - }, -#endif - { } -}; - static int pstore_compress(const void *in, void *out, unsigned int inlen, unsigned int outlen) { @@ -291,36 +187,31 @@ static void allocate_buf_for_compression(void) char *buf; /* Skip if not built-in or compression backend not selected yet. */ - if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend) + if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !compress) return; /* Skip if no pstore backend yet or compression init already done. */ if (!psinfo || tfm) return; - if (!crypto_has_comp(zbackend->name, 0, 0)) { - pr_err("Unknown compression: %s\n", zbackend->name); - return; - } - - size = zbackend->zbufsize(psinfo->bufsize); - if (size <= 0) { - pr_err("Invalid compression size for %s: %d\n", - zbackend->name, size); + if (!crypto_has_comp(compress, 0, 0)) { + pr_err("Unknown compression: %s\n", compress); return; } + /* Worst-case compression should never be more than uncompressed. */ + size = psinfo->bufsize; buf = kmalloc(size, GFP_KERNEL); if (!buf) { pr_err("Failed %d byte compression buffer allocation for: %s\n", - size, zbackend->name); + size, compress); return; } - ctx = crypto_alloc_comp(zbackend->name, 0, 0); + ctx = crypto_alloc_comp(compress, 0, 0); if (IS_ERR_OR_NULL(ctx)) { kfree(buf); - pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name, + pr_err("crypto_alloc_comp('%s') failed: %ld\n", compress, PTR_ERR(ctx)); return; } @@ -330,7 +221,7 @@ static void allocate_buf_for_compression(void) big_oops_buf_sz = size; big_oops_buf = buf; - pr_info("Using crash dump compression: %s\n", zbackend->name); + pr_info("Using crash dump compression: %s\n", compress); } static void free_buf_for_compression(void) @@ -818,27 +709,10 @@ static void pstore_timefunc(struct timer_list *unused) pstore_timer_kick(); } -static void __init pstore_choose_compression(void) -{ - const struct pstore_zbackend *step; - - if (!compress) - return; - - for (step = zbackends; step->name; step++) { - if (!strcmp(compress, step->name)) { - zbackend = step; - return; - } - } -} - static int __init pstore_init(void) { int ret; - pstore_choose_compression(); - /* * Check if any pstore backends registered earlier but did not * initialize compression because crypto was not ready. If so, -- 2.34.1
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